<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		.main{width: 100px;height: 100px;margin-top: 100px;margin-left: 200px;
			background: red;
            /*border-radius: 100% 0 0 0 ;*/
            position: relative;
            z-index: 2;
		}
		.small{
			position: absolute;top: -50%;left: -50%;right: -50%;bottom: -50%;
			background: blue;
			z-index: 1;
			/*transform: scale(.5);*/
		}
		.box{
			position: fixed;;bottom: 0;width: 100%;background: red;height: 100px;
		}
		.smallBox{position: absolute;;right: 10px;top: -100px;;
            border-width: 10px 20px 0;
            /*border-width: 10px;*/
			border-color: blue transparent  transparent;border-style:solid
			}
        .shadow{
        	width: 100px;height: 100px;position: absolute;top: 50%;left: 50%;
        	right: 50%;bottom: 50%;transform: translate(-50%);
        	box-shadow: 0px 0px 10px 100px red ;
        }
	</style>
</head>
<body>
	<div class="main">
		<div class="small"></div>
	</div>
	<div class="box">
		<div class="smallBox"></div>
	</div>
	<div class="shadow">
		阴影
	</div>
</body>
</html>